Why scrape when you can grind?

[CarbideBob]

The one with that speed is a small 5 axis.
The larger ones are a tad slower than 2000 ips

Of note I politely asked if rapids or cutting feedrates. There may be a fair amount of difference.
I have customers with mills that will cut at 2000 IPM. They are not box way and do not have coarse pitch ball screws.
Rapids are nice, fast tool changes are nice, but often cutting metal is where the money is made.
Can these machines hit 2000 IPM in a 0.250 rapid move as used in HSM? What is that in Gs?
My in house cnc fitted surface grinders with flat ways will do 1200 ipm rapids but never going to hit anywhere near that in a short move.
Bob

 

[DavidScott]

Of note I politely asked if rapids or cutting feedrates. There may be a fair amount of difference.
I have customers with mills that will cut at 2000 IPM. They are not box way and do not have coarse pitch ball screws.
Rapids are nice, fast tool changes are nice, but often cutting metal is where the money is made.
Can these machines hit 2000 IPM in a 0.250 rapid move as used in HSM? What is that in Gs?
My in house cnc fitted surface grinders with flat ways will do 1200 ipm rapids but never going to hit anywhere near that in a short move.
Bob

Those are rapids, not feeds. Agree that rapids are over rated but Kitamuras are quite stout and will remove metal just fine. Mine is a 30 taper and I have yet to make it squeal, after 9 years so far. I do love the robustness of box ways.

 

[EmGo]

Those are rapids, not feeds. Agree that rapids are over rated but Kitamuras are quite stout and will remove metal just fine. Mine is a 30 taper and I have yet to make it squeal, after 9 years so far. I do love the robustness of box ways.

We had two OKK's with box ways and they also cook. But the one that's really impressive is a Landis cam grinder with hydrodynamic ... take two ground surfaces and pump oil between them, now that's some nice ways !

 

[CarbideBob]

Those are rapids, not feeds. Agree that rapids are over rated but Kitamuras are quite stout and will remove metal just fine. Mine is a 30 taper and I have yet to make it squeal, after 9 years so far. I do love the robustness of box ways.

And I agree that these are very nice machines across the board.
I did not want to say them bad by any stretch.
Just that rapids are marketing talk. Across every brand or make.
Been in arguments with sales/marketing more than once and what they want to put out. Engineering always looses this battle.
Bob

 

[dcsipo]

Of note I politely asked if rapids or cutting feedrates. There may be a fair amount of difference.
I have customers with mills that will cut at 2000 IPM. They are not box way and do not have coarse pitch ball screws.
Rapids are nice, fast tool changes are nice, but often cutting metal is where the money is made.
Can these machines hit 2000 IPM in a 0.250 rapid move as used in HSM? What is that in Gs?
My in house cnc fitted surface grinders with flat ways will do 1200 ipm rapids but never going to hit anywhere near that in a short move.
Bob

I am not sure . Just another CNC with scraped box ways. Prolly real nice.

 

[empower]

I think grinding is a great way to rough something in, plus not many have a grinder big enough.

I know a few shops that have really big grinders that could do a nice/OK job of it.

this is pretty important IMO. when it comes to building machines, especially large ones, you'd be hard pressed to find a grinder large enough to grind the ways/guides on a large casting, especially on many different surfaces that are angled/perpendicular etc. at a certain point it becomes easier/more efficient to scrape than do multiple CRITICAL setups in ginormous grinding machines.

 

[52 Ford]

this is pretty important IMO. when it comes to building machines, especially large ones, you'd be hard pressed to find a grinder large enough to grind the ways/guides on a large casting, especially on many different surfaces that are angled/perpendicular etc. at a certain point it becomes easier/more efficient to scrape than do multiple CRITICAL setups in ginormous grinding machines.

Right. Look at a machine like Keith Rucker's metal planer (check YouTube). He had parts sent out for grinding and THEN scraped it in. I forgot if he mentioned what sort of PPI he scraped it, too. Been a while since I saw the video. I know he scraped it for contact, not oil.

 

[Tyrone Shoelaces]

We had two OKK's with box ways and they also cook. But the one that's really impressive is a Landis cam grinder with hydrodynamic ... take two ground surfaces and pump oil between them, now that's some nice ways !

I worked on a couple of Hor Bores that had the same system but we called it “ hydrostatic “.

Regards Tyrone.

 

[dcsipo]

Right. Look at a machine like Keith Rucker's metal planer (check YouTube). He had parts sent out for grinding and THEN scraped it in. I forgot if he mentioned what sort of PPI he scraped it, too. Been a while since I saw the video. I know he scraped it for contact, not oil.

Probably 20 PPI, based on the Richard King school of scraping, the minimum for static and sliding machine surfaces. You do 40 or higher PPI for reference surfaces.

 

[dcsipo]

We had two OKK's with box ways and they also cook. But the one that's really impressive is a Landis cam grinder with hydrodynamic ... take two ground surfaces and pump oil between them, now that's some nice ways !

Wonder how good a way one could make using SI3N4, AL2O3 and light oil pumped in between. I know that both can be deposited on a steel or iron substrate.

 

[hvnlymachining]

JSCPM
I understand your bewilderment. The saddle ways on my '78 American lathe aren't scraped, but the tailstock ways are. Why are some ways sufficient being smooth as glass and others need scraped marks. The saddle ways are tool steel, and so don't wear as fast. But that doesn't change the fact that they are smooth.

In regards to the American Pacemakers ( tool steel way models), they were scraped for straightness along the tongue that holds the hardened ways on the bed. And the underside of the carriage ways are scraped for oil retention rather than the lathe bed ways. This also helps with making a more precise fit between the carriage and bed ways.

 

[TGTool]

IIRC Moore used both grinding and scraping where they thought each was appropriate. I think the jig borers and jig grinders had inverted ways in the base that were ground. But the ground ways were hardened inserts and the base where they installed was scraped for fit and alignment.

 

[Richard King]

Right. Look at a machine like Keith Rucker's metal planer (check YouTube). He had parts sent out for grinding and THEN scraped it in. I forgot if he mentioned what sort of PPI he scraped it, too. Been a while since I saw the video. I know he scraped it for contact, not oil.

I taught Keith Rucker to scrape and he did both! Scraped for PPI (high points per inch) and the low points for oil pockets. You want equal amounts. I teach 40 to 60%. Those pockets or low oil spots average measured depth is .0005".

 

[Richard King]

IIRC Moore used both grinding and scraping where they thought each was appropriate. I think the jig borers and jig grinders had inverted ways in the base that were ground. But the ground ways were hardened inserts and the base where they installed was scraped for fit and alignment.

In the later years, Moore used bolt on steel rails they that were bolted to scraped surfaces. If the rails were still a little out of alignment, they lapped them with diamond paste with small lapping plates. Fellow gear testers used the same method using hardened rails.

 

[DavidScott]

And I agree that these are very nice machines across the board.
I did not want to say them bad by any stretch.
Just that rapids are marketing talk. Across every brand or make.
Been in arguments with sales/marketing more than once and what they want to put out. Engineering always looses this battle.
Bob

We are in total agreement with rapids. I have noticed that if I turn my rapids down to 50% my cycle times only go up by 1-2%, and it is not because of slow accel/decel like a Fadal. What drives my nuts is when the MTB uses coarse pitch ball screws to get those high rapids. Kitamuara does not cut that corner at all. They may have very fast rapids but not at the expense of stiffness or longevity, IME. The only issue I have had is it kills the rubber bumpers in the way covers, and Kitamura does not sell way cover parts, only complete units.

 

[michiganbuck]

One thing good about scraping is that when a surface grinder goes whacky after 20 years and begins to run .0005 out one can fix it with some elbow grease.

 

[CalG]

Half and half seems to be a great combination.

Ground ways and scraped saddle is a good choice on a lathe or mill.

Those LeBlond replaceable ways were a gimmick, they never needed replacing ;-)

 

[dcsipo]

Half and half seems to be a great combination.

Ground ways and scraped saddle is a good choice on a lathe or mill.

Those LeBlond replaceable ways were a gimmick, they never needed replacing ;-)

Ya know , the advertisement might have been a gimmick, but replaceable ways have an interesting installation advantage. The ability to adjust the substrate under the precision surface is a plus. Other than that the replaceable nature is almost never used.

 

[michiganbuck]

Ya know , the advertisement might have been a gimmick, but replaceable ways have an interesting installation advantage. The ability to adjust the substrate under the precision surface is a plus. Other than that the replaceable nature is almost never used.

But it does allow hard way surface.

 

[Tyrone Shoelaces]

But it does allow hard way surface.

Running against saddle ways that aren’t particularly hard.

Regards Tyrone.